how to inject FastAPI bearer instances into Depends

Hi, I’m currently struggeling on how to get this to work.

I have a third party “factory method” that provides me with a method I can use in FastAPI’s Depends resolver

from third_party import auth_factory

@app.get("/foo")
def foo(user = Depends(auth_factory(scope="read", extractor = some_token_extractor ))):
    doSomething()

the oauth_factory produces as callable with fastapi know signature

def user_checker(oauth_header:HTTPAuthorizationCredentials = Security(bearer))
   ...
   return user

My problem now is when I want the some_token_extractor be provided by python-dependency-injector

something like this does not work:

user_detail_extractor = Provide[Container.user_detail_extractor]

@app.get("/with_di")
def with_di(user = Depends(auth_factory(scope="read", extractor = user_detail_extractor ))):

    return {
        "user": user["username"]
    }

class Container(DeclarativeContainer):

    user_detail_extractor = providers.Callable(some_di_extractor, some_config="bla")

I have a full demo setup here https://github.com/mxab/fastapi-di-depends-issue/tree/main/fastapi_di_depends_issue

but I cannot get this test work: https://github.com/mxab/fastapi-di-depends-issue/blob/main/tests/test_fastapi_di_depends_issue.py#L27

Does this in general not work or what is it I’m missing

Thanks very much in advance

[Digoya]

I ended up with something like this:

class ApplicationContainer(containers.DeclarativeContainer):
    partial_service = providers.Factory(Service, kw="foo")

@inject
def service(fastapi_dep=Depends(FastAPI_dependency), service=Depends(Provider[ApplicationContainer.partial_service])):
    return service(fastapi_dep)

ApplicationContainer.service = service

Later can be used as:

@router.post("/route")
@inject
async def handler(service=Depends(ApplicationContainer.service)):
    print(service)

[adriangb]

I think part of the trouble stems from the fact that Depends looks for an instance of Security at compile time, before anything is injected. I believe it would get an instance of whatever Provide[Container.bearer] returns, which is not going to be an instance of fastapi.security.base.SecurityBase.